title: Immunoglobulin heavy chain genes: demethylation accompanies class switching.
abstract: The methylation of immunoglobulin heavy chain genes was examined before and after class switching, by using the Hpa II/Msp I restriction mapping technique. The mu, delta, and gamma 1 genes all are methylated in cells that do not express them but are demethylated when they are expressed. In particular, the delta gene remains methylated, and thus presumably untranscribed, in a cell line that probably represents an early stage of B-cell differentiation and produces only mu heavy chains. Because mu and delta RNAs are cotranscribed from a single complex transcription unit at a later stage of B-cell differentiation, this finding implies that the mu-plus-delta complex transcription unit is of variable length.
mesh_terms: D044503:5-Methylcytosine; D000818:Animals; D002460:Cell Line; D003596:Cytosine / Q000031:analogs & derivatives* / Q000378:metabolism; D005786:Gene Expression Regulation; D005796:Genes; D007127:Immunoglobulin Constant Regions / Q000235:genetics; D007143:Immunoglobulin Heavy Chains / Q000235:genetics*; D007138:Immunoglobulin delta-Chains / Q000235:genetics; D007142:Immunoglobulin gamma-Chains / Q000235:genetics; D007148:Immunoglobulin mu-Chains / Q000235:genetics; D008099:Liver / Q000502:physiology; D051379:Mice; D014158:Transcription, Genetic
chemical_list: D007127:Immunoglobulin Constant Regions; D007143:Immunoglobulin Heavy Chains; D007138:Immunoglobulin delta-Chains; D007142:Immunoglobulin gamma-Chains; D007148:Immunoglobulin mu-Chains; D044503:5-Methylcytosine; D003596:Cytosine